When you raid another camp, you can see an overview of their buildings. Take note of where their defensive structures are located (Drakecapults, Troll Towers, etc.). Target those buildings first to remove threats to your dragons. When you select a dragon, tap a tower to have it immediately attack that specific target. You can also do this at when a dragon switches targets. Ground units are recruited through a summoning portal. Although they are not as powerful as your dragons, they will aid your offense. You can eventually build a Boot Camp to level up your units and strengthen them. When deployed, have your dragons and ground units work together. Use your dragons to destroy walls that are out of range of defense towers, and allow your ground units to invade. Then, have the ground units keep enemy defenses busy to allow your dragons to operate freely.